548 CAMBRIAN BRACHIOPODA. 



I have observed, and none of the specimens studied by him showed the area of either the ventral 

 or dorsal valve. 



As the result of a comparison of a series of specimens of L. (L.) acuminata from the Potsdam 

 sandstone and the base of the " Calcif erous " in Saratoga, Washington, Franklin, and Jsfferson 

 counties, New York, and from the same horizon in Ontario, Canada, with a large series of 

 specimens from the "St. Croix sandstone" of Wisconsin, I was led [1897a, p. 404] to conclude 

 that "Lingula finnaformis" Owen was a synonym of LinguMla (Lingulepis) acuminata (Con- 

 rad), thus making L. (L.) acuminata the type of the subgenus Lingulepis, the original description 

 of the subgenus being based upon specimens from the "St. Croix sandstone" of Wisconsin. 



It is hardly practicable to illustrate all of the varieties of L. {L.) acuminata (Conrad) as 

 they occur in widely distributed localities. The shells appear to have varied in size, thickness, 

 convexity, and outline at various localities, and often in the same locality in different layers, 

 probably owing to the character of food supply and the vitality of the individual animals. 

 Very fine specimens of the casts of young shells of the narrow, elongate form occur at Mount 

 Washington, Eau Claire, Wisconsin. 



The species ranges from western Vermont, New York, and eastern Canada, westward across 

 the upper Mississippi Valley to the Black Hills of South Dakota, the Bighorn Mountains of 

 Wyoming, and the Rocky Mountains of central Colorado. In the Appalachian region it ranges 

 southward to Tennessee and Alabama, and westward to the Arbuckle and Wichita mountains of 

 Oklahoma, and the Franklin Range near El Paso, Texas. Its vertical range appears to have 

 been from the upper portion of the Middle Cambrian in the Mississippi Valley and the Black 

 HiUs to the lower layers of the " Calciferous " of the Ordovician in New York and Canada. 



A number of shells from the Upper Cambrian rocks of Nevada come within the rather wide 

 range of variation of this species. I was at first inclined to place them as a variety, but after 

 extended comparison with a series of specimens from New York and Wisconsin, decided that 

 nothing would be gained by so doing. A few figures on Plate XXXIV, figures 4, 4a-e, illus- 

 tsate the wide variation in form of the Nevada shell, a variation comparable with that from 

 the typical locality in New York. 



A fine series of specimens illustrating the narrow and broad forms has been collected from 

 the limestone in the upper portion of the Reagan sandstone (Upper Cambrian), at the north- 

 west extremity of the Arbuckle Mountains, Oklahoma. 



Dwight [1886, p. 208], in speaking of the Upper Cambrian fauna near Poughkeepsie, New 

 York, said: 



It will be observed, as has been suggested to me by Whitfield, that the fauna of this locality forms a connecting 

 link between the Potsdam fossils of the Appalachian region and that of the more western States. Thus, the Lingulella 

 pinnaformis of Wisconsin and other western localities is here mingled with Lingulepis minima and acuminata of New 

 York State. 



Dwight's remark that the species "Lingulella pinnaformis" occurs mingled with "Lingu- 

 lepis minima" and "L. acuminata" proves that all the varieties of Lingulella (Lingulepis) 

 acuminata occur at the Dutchess County locality. 



Formation and locality. — Ordovician and TTpper Cambrian: (338u) Strata from the upper layers of the Potsdam 

 sandstone to the lower portion of the "Calciferous sandrock" at Chateaugay Falls, Franklin County, New York. 



Upper Cambrian: (392e [Billings, 1856, p. 34]) Sandstone on lot 22, ninth concession, township of Bastard; (392d 

 [Billings, 1856, p. 34]) sandstone on lot 11, eleventh concession, township of Lansdowne; and (392b [Matthew, 1895b, 

 p. 258]) sandstone (corresponding to the passage beds above the massive Potsdam sandstone at Chateaugay Falls) at 

 Beverly, township of Bastard; all in the county of Leeds, Ontario, Canada. 



(392) Potsdam sandstone at Burgess; (392m) sandstone on the east shore of Missisquoi Bay, 1.5 miles (2.4 km.) 

 south of Phillipsbm-gh, Province of Quebec; and (392n) sandstone in eastern Canada (exact locality unknown); all in 

 Canada. 



(16n) Interformational conglomerates and shales in Adams pasture, 0.5 mile (0.8 km.) west of Main Street, on 

 Lake Street, St. Albans, Franklin County, Vermont. 



(76) Arenaceous limestone at Hoyt's quarry, 4 miles (6.4 km.) west of Saratoga Springs, Saratoga County; (76a) 

 arenaceous limestone in a railroad quarry 1 mile (1.6 km.) north of Saratoga Springs, Saratoga County; (109) sandstone 

 25 feet (7.6 m.) above the Archean, 1.5 miles (2.4 km.) south of Deweys Bridge, on the Champlain Canal, Washington 



